Meeting Abstract

117.4  Monday, Jan. 7  Immune costs of the physiological stress response are affected by cross-generational exposure to stress MCCORMICK, G.L.*; LANGKILDE, T.; Pennsylvania State University; Pennsylvania State University glm173@psu.edu

An organism’s ability to respond to stressors is integral to its survival and reproductive fitness, and is increasingly important in light of environmental change. An animal’s physiological response to stress is generally adaptive. For example, the production of glucocorticoid hormones, including corticosterone (CORT), can trigger survival-enhancing behavior. However, chronic stress, such as that elicited by frequent encounters with predators, can divert energy from other important processes, such as immune function. Additionally, it is possible that the costs of chronic stress differ between populations that have evolved in high- versus low-stress environments. We investigated the tradeoff between stress and immune function in male Eastern fence lizards (Sceloporus undulatus) in both high- and low-stress sites. This difference in field stress (measured as baseline CORT levels) is associated with the long-term presence or absence of predatory invasive fire ants (Solenopsis invicta). We experimentally manipulated CORT levels by applying exogenous CORT, or a control vehicle, to lizards daily for 23 days, and then measured two immune parameters (complement bacterial lysis and antibody hemagglutination). Immune function of lizards from low-stress sites appears to be fairly robust to stress. However, lizards from high-stress sites had a stress-sensitive immune response, and the nature of this response varied between the two immune measures. This suggests that cross-generational exposure to stressors can affect tradeoffs between the physiological response to a stressor and other nutrient-demanding processes, such as immune function.